I've been playing a lot of Aliens versus Predator for the 360. I think it's a pretty solid 8/10.
Keep in mind I grew up a big fan of both movie franchises, so I get a kick out of the detail these developers put into this. They did a great job of making you feel like you're in those worlds.
It might now appeal nearly as much to outsiders, but I still think the online gameplay is pretty good (though flawed).